Fix crash after Launcher drag/drop (take 3 - no unit test)

ui/app_list/views/apps_grid_view.cc

 // Copyright (c) 2012 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "ui/app_list/views/apps_grid_view.h"
 
 #include <algorithm>
 #include <set>
 #include <string>
 
@@ skipping 690 matching lines @@
       } else if (IsValidIndex(reorder_drop_target_)) {
         MoveItemInModel(drag_view_, reorder_drop_target_);
       }
     }
   }
 
   if (drag_and_drop_host_) {
     // If we had a drag and drop proxy icon, we delete it and make the real
     // item visible again.
     drag_and_drop_host_->DestroyDragIconProxy();
-    if (landed_in_drag_and_drop_host) {
-      // Move the item directly to the target location, avoiding the "zip back"
-      // animation if the user was pinning it to the shelf.
-      int i = reorder_drop_target_.slot;
-      gfx::Rect bounds = view_model_.ideal_bounds(i);
-      drag_view_->SetBoundsRect(bounds);
+    // Issue 439055: MoveItemToFolder() can sometimes delete |drag_view_|
+    if (drag_view_) {
+      if (landed_in_drag_and_drop_host) {
+        // Move the item directly to the target location, avoiding the
+        // "zip back" animation if the user was pinning it to the shelf.
+        int i = reorder_drop_target_.slot;
+        gfx::Rect bounds = view_model_.ideal_bounds(i);
+        drag_view_->SetBoundsRect(bounds);
+      }
+      // Fade in slowly if it landed in the shelf.
+      SetViewHidden(drag_view_, false /* show */,
+                    !landed_in_drag_and_drop_host /* animate */);
     }
-    // Fade in slowly if it landed in the shelf.
-    SetViewHidden(drag_view_,
-                  false /* show */,
-                  !landed_in_drag_and_drop_host /* animate */);
   }
 
   // The drag can be ended after the synchronous drag is created but before it
   // is Run().
   CleanUpSynchronousDrag();
 
   SetAsFolderDroppingTarget(folder_drop_target_, false);
   ClearDragState();
   AnimateToIdealBounds();
 
@@ skipping 1436 matching lines @@
 
 void AppsGridView::SetAsFolderDroppingTarget(const Index& target_index,
                                              bool is_target_folder) {
   AppListItemView* target_view =
       GetViewDisplayedAtSlotOnCurrentPage(target_index.slot);
   if (target_view)
     target_view->SetAsAttemptedFolderTarget(is_target_folder);
 }
 
 }  // namespace app_list